Do I need to be proficient in Czech and Slovenian to point out that loanwords exist in the English language with letters and diacritics that aren't in the English alphabet? My point stands either way, and your response does nothing to address that. In fact, you're kind of proving yourself wrong about Türkiye. If I'm remembering correctly from my time in Czechia, Čapek would be pronounced "Chapek," but I could be wrong and that still wouldn't change the fact that English includes loanwords with diacritics that aren't in the English alphabet. I haven't been to Slovenia, so I can't help you with Žižek. But again, that doesn't change the fact that English includes loanwords with diacritics that aren't in the English alphabet.